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Show ANNOTATIONS AND ADDITIONS. 361 The Escallonias-among which E. myrtilloides, E. tubar, and E. fl.oribunda are the ornament of the Paramos, and by their physiognomy remind the beholder strongly of the myrtle-form-once constituted, in combination with the European and South American Alp-roses (Rhododendrum and Befaria), and with Clethra, Andromeda, and Gaylussaccia buxifolia, the family of Ericere. Robert Brown (see the Appendix to Franklin's Narrative of a Journey to the Shores of the Polar Sea, 1823, p. 765) has raised them to the rank of a separate family, which Kunth places between Philadelphere and Hamamelidere. The Escallonia fl.oribunda offers in its geographical distribution one of the most striking examples, in the habitat of the plant, of proportion between distance from the Equator and vertical elevation above the level of the sea. In making this statement, I again support myself on the authority of my acute and judicious friend Auguste de St.-Hilaire (Morphologie vegetable, 1840, p. 52): "Messieurs de Humboldt et Bonpland ont decouvert dans leur expedition l'Escallonia fl.oribunda a 1400 toises par les 4° de latitude australe. Je l'ai retrouve par les 21° au Bresil dans un pays eleve, mais pourtant infiniment plus bas que les Andes du Perou: il est commun entre les 24°.50' et les 25°.55' dans les Campos Gerres, enfin je le revois au Rio de la Plata vers les 35°, au niveau meme I' ocean." Trees belonging to the group of Myrtacere-to which Melaleuca, Metrosideros, and Eucalyptus belong in the subdivision of Leptospermere- produce partially, either where the leaves are replaced by phyllodias (leaf-stalk leaves), or by the peculiar disposition or direction of the leaves relatively to the unswollen leaf-stalk, a distribution of stripes of light and shade unknown in our forests of round-leaved trees. The first botanical travellers who visited New Holland were struck with the singularity of the effect thus produced. Robert Brown was the first to show that this strange appearance arose from the leaf-stalks (the phyllodias of the Acacia longifolia and A. suaveolens) being expanded in a vertical direction, and from the circumstance that the light, instead of falling on horizontal surfaces, falls on and passes between vertical ones. ( Adrien de J ussieu, Cours de Botanique, pp. 106, 120, and 700; Darwin, Journal of Researches, 1845, p. 433.) Morphological laws in the development of the leafy 31 |
